Low-Level Design: Splitwise Expense Sharing App
7 min read Low-Level Design: Splitwise (Expense Sharing App) The Splitwise LLD asks you to model a shared expense tracker where users add […] Read article
System Design
System Design
Low-Level Design: Pub/Sub Message Broker (Observer Pattern)
6 min read Low-Level Design: Pub/Sub Message Broker A Pub/Sub (Publish-Subscribe) message broker decouples producers from consumers through named topics. Producers publish events; Read article
System Design
Low-Level Design: Food Delivery App (DoorDash/Uber Eats) OOP Design
7 min read Low-Level Design: Food Delivery App (DoorDash / Uber Eats) The food delivery app LLD question asks you to model the Read article
System Design
System Design: Consistent Hashing Explained with Virtual Nodes
7 min read Consistent Hashing: System Design Deep Dive Consistent hashing is a distributed hashing scheme that minimises key remapping when nodes are Read article
System Design
Low-Level Design: Task Scheduler (Priority Queue, Thread Pool, Retries)
6 min read Low-Level Design: Task Scheduler The Task Scheduler is a recurring LLD interview question at companies like Google, Meta, Airbnb, and Read article
Algorithms
Interval and Scheduling Interview Patterns (2025)
5 min read Interval Problem Fundamentals Interval problems involve ranges [start, end] and ask about overlaps, merges, insertions, or optimal scheduling. The key Read article
System Design
Low-Level Design: Social Network Friend Graph (OOP Interview)
9 min read Problem Statement Design a social network graph system like LinkedIn’s connection model or Facebook’s friends graph. Users can send friend Read article
System Design
Low-Level Design: Stock Order Book (Trading System OOP Interview)
8 min read Problem Statement Design a stock trading order book system. Traders submit buy and sell orders at specific prices and quantities. Read article
Algorithms
Dynamic Programming: Knapsack and Subset Sum Patterns (2025)
7 min read The 0/1 Knapsack Pattern The 0/1 Knapsack problem is one of the most important DP patterns — its structure appears Read article
System Design
Low-Level Design: Online Auction System (OOP Interview)
9 min read Problem Statement Design an online auction system like eBay. Sellers list items with a starting price, auction duration, and reserve Read article
System Design
System Design Interview: Design a Search Autocomplete (Typeahead)
8 min read Problem Statement Design a search autocomplete (typeahead) system like Google Search suggestions or Amazon product search. As a user types, Read article
System Design
Low-Level Design: Ride-Sharing App (Uber / Lyft OOP Interview)
8 min read Problem Statement Design the core backend of a ride-sharing app like Uber or Lyft. A rider requests a trip with Read article
System Design
Low-Level Design: Parking Lot System (OOP Interview)
8 min read Problem Statement Design an object-oriented parking lot system. The lot has multiple levels, each with multiple spots of different sizes Read article
System Design
System Design Interview: Design a Leaderboard / Top-K System
7 min read System Design: Top-K / Leaderboard (Heavy Hitters) Top-K problems appear in many real-world systems: game leaderboards, trending hashtags, most-viewed videos, Read article
System Design
System Design Interview: Design a Geo-Proximity Service (Yelp / Nearby)
6 min read System Design: Geo-Proximity Service (Yelp / Google Maps Nearby) A geo-proximity service finds places (restaurants, drivers, stores) near a given Read article